JP4506799B2 - Exhaust device for internal combustion engine for vehicle - Google Patents

Description

  The present invention relates to an exhaust device for an internal combustion engine for a vehicle, and more particularly, to an exhaust gas for an internal combustion engine for a vehicle in which exhaust gas from a multi-cylinder internal combustion engine mounted on the vehicle is divided into one and the other silencer by a branch pipe. Relates to the device.

  Recently, in an exhaust system for an internal combustion engine for a vehicle, since the capacity of the silencer is easy to increase and the design is excellent, the exhaust pipe is branched to the left and right at the downstream side of the exhaust pipe. There are some which employ a so-called two-exhaust exhaust system in which a silencer is attached to the rear and exhausted from the left and right exhaust ports at the rear of the vehicle.

  As a conventional exhaust device for this type of vehicle internal combustion engine, for example, exhaust pipes from a pair of banks of a V-type engine (internal combustion engine) are once joined together and passed through a catalyst device and a pre-muffler, An exhaust gas that is diverted to the left and right rear mufflers by a branch pipe and silenced is known (see, for example, Patent Document 1).

In order to block the roll vibration during engine operation, ball joints (spherical pipe joints) that allow relative swinging of the front and rear exhaust pipes are mounted on the upstream side of the left and right exhaust paths. A type in which a flexible pipe is mounted immediately after one ball joint to absorb vibration displacement is known (for example, see Patent Document 2).
JP 2005-248767 A JP 09-317461 A

  However, in the conventional exhaust system for a vehicle internal combustion engine as described above, when the downstream side of the exhaust pipe is diverted to the left and right rear mufflers by the branch pipe, the left and right exhaust balance (equal exhaust amount) Therefore, the left and right rear mufflers and branch pipes with a relatively large mass vibrate at the phase where the vibrations overlap. It was easy. For this reason, in a specific vibration frequency range, for example, the idle vibration range, vibrations of the left and right rear mufflers and branch pipes are intensified and transmitted to the vehicle body side, causing uncomfortable vibration on the passenger compartment floor near the driver's seat. There was a problem that would occur. In particular, when the front pipes connected to the front and rear exhaust manifolds are unequal in length, such as a V-type horizontal engine, there are many restrictions on the arrangement of the ball joints on the downstream end side, and the engine vibration is also reduced. For example, vibration is likely to occur on the floor under the driver's feet in an idle vibration range of 30 Hz to 40 Hz of a 6-cylinder engine, which becomes noticeable due to vibration transmission from the left and right rear mufflers and the branch pipe side. There was a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust device for an internal combustion engine for a vehicle that can prevent unpleasant vibrations from being generated in an occupant due to an exhaust structure that diverts and exhausts air to one and the other silencer. .

In order to achieve the above object, an exhaust system for an internal combustion engine for a vehicle according to the present invention includes: (1) one exhaust pipe downstream of a branch point in the exhaust pipe and the other exhaust pipe of the internal combustion engine mounted on the vehicle; It is branched into a branch pipe, one of the muffler to the branch pipes of the one, in the exhaust system of the second branch pipe to the other muffler respectively mounted to the vehicle internal combustion engine, and the one branch pipe the A pipe joint that allows partial bending of one of the branch pipes upstream of the silencer mounted on one of the other branch pipes, and the one branch pipe; Bending rigidity and mass of the one branch pipe and the other branch pipe so that the vibrations of both branch pipes cancel each other at the branch point when the other branch pipe is vibrated in a specific vibration frequency region. Characterized in that at least one of them is different

  With this configuration, when exhaust is sequentially performed from a cylinder that has undergone an explosion stroke during operation of the internal combustion engine, one branch pipe equipped with a silencer and the other branch pipe are vibrated by pulsation of exhaust pressure in the exhaust pipe, etc. However, in a specific vibration frequency range, the vibrations of one branch pipe and the other branch pipe cancel each other at the branch point, and the amplitude on the upstream side of the branch point is suppressed, and vibration transmission to the vehicle body side is suppressed. It is suppressed. Therefore, unpleasant vibrations are prevented from occurring in the passenger due to the exhaust structure that diverts and exhausts air to one and the other silencers in a specific vibration frequency region. In addition, by making at least one of the bending rigidity and the mass different, when the one branch pipe and the other branch pipe are vibrated in a specific vibration frequency region, the vibrations of both branch pipes cancel each other at the branch point. In addition, the respective resonance frequencies can be set to shift the vibration phases of both branch pipes in a specific vibration frequency region.

Furthermore, by providing a pipe joint that allows partial bending of one of the branch pipes, the arrangement of one branch pipe and the other branch pipe and the length of the exhaust pipe line are made substantially equal, while both branch pipes are The resonance frequency and the vibration mode can be easily varied so as to vibrate almost in opposite phases in a specific vibration frequency region, and vibration transmission to the vehicle body side can be more effectively suppressed. In addition, by adjusting the bending rigidity of the pipe joint portion, it is possible to easily adjust the resonance frequency of the branch pipe on which the pipe joint is mounted.

The exhaust apparatus for an internal combustion engine for a vehicle described in ( 1 ) above is: ( 2 ) the pipe joint is provided with a seal member provided on one end side pipe portion of the one of the branch pipes, and either one of the branches. An engagement member provided on the other end side tube portion of the tube, and a spring element interposed between the one end side tube portion and the other end side tube portion so as to bias the seal member to the engagement member; It is preferable that the one end side pipe part and the other end side pipe part are relatively pivotably connected in a state where the engagement member is in contact with the seal member.

  With this configuration, the one end side pipe part and the other end side pipe part of either one of the branch pipes are relatively swung with the required bending rigidity while preventing leakage of exhaust gas at the pipe joint part by the seal member. Can be possible.

In the exhaust device for an internal combustion engine for a vehicle described in ( 2 ) above, ( 3 ) the engagement member and the seal member are in spherical contact, and any one of the branch pipes is arbitrarily bent More preferably it is possible in the direction.

  With this configuration, the degree of freedom of the mounting posture of the branch pipe and the silencer is increased, and the pipe joint portion can be reliably sealed.

The exhaust system for an internal combustion engine for a vehicle described in ( 1 ) above, and ( 4 ) the pipe joint includes one end side pipe portion of the one of the branch pipes and the other end side of the one of the branch pipes. It may consist of a flexible tubular member interposed between the tube portion.

  Even with this configuration, one end side pipe part and the other end side pipe part of either one of the branch pipes can be relatively swung with a required bending rigidity while preventing leakage of exhaust gas at the pipe joint part. can do.

( 5 ) In the exhaust device for an internal combustion engine for a vehicle according to any one of (1) to ( 4 ), ( 5 ) upstream from a branch point where the exhaust pipe branches into the one branch pipe and the other branch pipe. And the one silencer and the other silencer are supported on the vehicle body side of the vehicle, the one branch pipe and the other branch pipe. However, it is good that it is supported by the intermediate part and the one and the other silencers.

  With this configuration, one branch pipe and the other branch pipe are supported in a state where they can vibrate according to their respective bending rigidity.

According to the present invention, vibrations in a specific vibration frequency region between one branch pipe and the other branch pipe each equipped with a silencer cancel each other at those branch points so that vibration transmission to the vehicle body side is suppressed. Therefore, it is possible to provide an exhaust device for an internal combustion engine for a vehicle that can prevent an unpleasant vibration from being generated in an occupant due to an exhaust structure that diverts and exhausts air to one and the other silencers. Moreover, while the arrangement of one branch pipe and the other branch pipe and the length of the exhaust pipe line are substantially equal, the resonance frequency and vibration mode of both branch pipes are different so as to vibrate in almost opposite phases in a specific vibration frequency region. The vibration transmission to the vehicle body side can be more effectively suppressed, and the resonance frequency of the branch pipe to which the pipe is attached can be easily adjusted by adjusting the bending rigidity of the pipe joint portion.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing a schematic configuration of an exhaust device for an internal combustion engine for a vehicle according to a first embodiment of the present invention, and FIG. 2 shows an exhaust pipe layout of the exhaust device for the internal combustion engine for a vehicle. FIG. 3 is a partial cross-sectional front view of a pipe joint attached to one of the branch pipes.

  As shown in FIGS. 1 and 2, in the present embodiment, an engine 11 that is an internal combustion engine for a vehicle is constituted by, for example, a horizontally-arranged V-type 6-cylinder multi-cylinder internal combustion engine (details not shown), It is supported by a vehicle body (not shown) of the vehicle 1 by left and right engine mounts (not shown) and an engine mount 15 on the rear side, and has a pair of banks 11a and 11b of three cylinders. The exhaust manifolds 12 and 13 disposed on both sides of the engine 11 are fastened to the banks 11a and 11b by fastening members (not shown), and exhaust gas is introduced into the exhaust manifolds 12 and 13 from the banks 11a and 11b of the engine 11. It is supposed to be discharged.

  Although not shown in detail, the exhaust manifold 12 includes a plurality of exhaust introduction portions connected to the exhaust ports of the first cylinder to the third cylinder formed in the bank 11a on the front side of the engine 11, and the exhausts. The exhaust manifold 13 has a plurality of exhaust pipes connected to the exhaust ports of the fourth cylinder to the sixth cylinder formed in the bank 11b on the rear side of the engine 11, respectively. And a collecting pipe portion for collecting the exhaust introduction portions.

  As shown in FIG. 2, the exhaust device for an internal combustion engine for a vehicle according to this embodiment includes a first front pipe 21 and a second front pipe 22 that introduce exhaust gas from the engine 11 through exhaust manifolds 12 and 13. . The first front pipe 21 has a longer pipe length than the second front pipe 22 and is connected to the collecting pipe portion of the exhaust manifold 12. Further, the second front pipe 22 having a pipe length shorter than that of the first front pipe 21 is connected to the collecting pipe portion of the exhaust manifold 13.

  The first front pipe 21 and the second front pipe 22 join at a joining point A and are connected to the center pipe 24 via a front ball joint 23. The merging here simply means a mechanical connection structure from the first front pipe 21 and the second front pipe 22 to the single center pipe 24, and the exhaust flowing in the first front pipe 21 and the second front pipe 22. For example, the gas may flow while being divided into left and right exhaust paths in the center pipe 24. That is, the center pipe 24 can be configured as a so-called dual exhaust pipe having a partition plate (not shown) that partitions and separates the left and right exhaust paths inside. It is possible that exhaust gases flowing in the first front pipe 21 and the second front pipe 22 are merged and mixed at the junction A, and can flow together in a single exhaust pipe formed in the center pipe 24. Needless to say.

  A catalyst device 25 for exhaust gas purification is attached to the center pipe 24 immediately after the front ball joint 23, and a sub muffler 26 having a relatively small muffler capacity is attached to a position separating a predetermined pipe length from the catalyst device 25. Yes. These catalyst device 25 and sub-muffler 26 are known ones. The center pipe 24 may be provided with another sub-muffler instead of the catalyst device 25.

  On the downstream side of the center pipe 24, there is a connecting pipe portion 31 that is, for example, flange-coupled to the downstream end portion of the center pipe 24. A rear pipe 30 branched to the crotch is provided. Note that the connecting pipe portion 31 can be coupled to the downstream end portion of the center pipe 24 via a vibration blocking mechanism such as a ball joint (see, for example, Patent Document 2).

  The rear pipe 30 constitutes the exhaust pipe 20 whose overall shape is shown in FIG. 2 together with the front pipes 21 and 22 and the center pipe 24, and the exhaust pipe 20 is connected to one branch pipe 32 downstream from the branch point B in the exhaust pipe 20. And the other branch pipe 33. One branch pipe 32 is fitted with one main muffler 36 (silencer), and the other branch pipe 33 is fitted with the other main muffler 37 (silencer).

  Here, the one branch pipe 32 and the other branch pipe 33 are arranged so that the vibrations of both the branch pipes 32 and 33 cancel each other out at the branch point B when being excited in a specific vibration frequency region. At least one of the bending stiffness and the mass of the tubes 32 and 33 is different. As a result, vibrations of both branch pipes 32 and 33 when one branch pipe 32 and the other branch pipe 33 are vibrated in a specific vibration frequency region due to exhaust pressure fluctuation (pulsation or the like) during idle operation. The phase is shifted.

  Specifically, a pipe joint 41 that allows partial bending of one branch pipe 32 is provided on the upstream side of the main muffler 36 attached to one branch pipe 32. Due to the presence of the pipe joint 41, the resonance frequency and vibration mode of one branch pipe 32 (including the silencer 36) are different from the resonance frequency and vibration mode of the other branch pipe 33 (including the silencer 37). In a specific vibration frequency region that causes different idle vibrations that are uncomfortable for the occupant, the vibration phases of the two branch pipes 32 and 33 are substantially shifted to opposite phases, and the vibrations of the two branch pipes 32 and 33 are at the branch point B. By canceling each other, vibration transmission to the upstream side is suppressed.

  As shown in FIG. 3, the pipe joint 41 includes a seal member 42 having a gasket function provided at one end side pipe portion 32 a of one of the branch pipes 32, and the other end side pipe of one of the branch pipes 32. An engaging member 43 provided in the portion 32b, and a spring element 44 interposed between the one end side tube portion and the other end side tube portion so as to bias the seal member 42 to the engaging member 43. Also has a vibration isolation function. And this pipe joint 41 gives the restoring force which maintains and returns the one end side pipe part 32a and the other end side pipe part 32b to the initial position in the state which made the engagement member 43 contact the seal member 42. While being relatively pivotable.

  Further, since the engagement member 43 has a concave spherical engagement surface, and the seal member 42 has a spherical engagement surface, the seal member 42 and the engagement member 43 are in spherical contact with each other. Thus, partial bending of one of the branch pipes 32 is possible in any direction.

  On the other hand, the exhaust pipe 20 is connected to the center pipe 24 at the connection pipe portion 31 upstream from the branch point B where the exhaust pipe 20 branches into the one branch pipe 32 and the other branch pipe 33, and is a center pipe that is an intermediate portion of the exhaust pipe 20. 24 is supported by a vehicle body side member (not shown) by mounting brackets m1 and m2 in the vicinity of both end portions. Each of the one main muffler 36 and the other main muffler 37 is supported by the vehicle body side member via mounting brackets m3 and m4, and one branch pipe 32 and the other branch pipe 33 are connected to the center pipe 24 and one and It is supported by the other main muffler 36, 37.

  Next, the operation will be described.

  When the exhaust gas is introduced into the first front pipe 21 and the second front pipe 22 from the exhaust manifolds 12 and 13 on both sides of the engine 11 during the operation of the engine 11, the exhaust gas that has passed through both the front pipes 21 and 22 enters the center pipe 24. The exhaust gas that has joined together and passed through the center pipe 24 is again diverted to the left and right one and the other branch pipes 32 and 33 by the rear pipe 30, and then silenced by the one and the other main mufflers 36 and 37, respectively. The air is discharged into the atmosphere through the exhaust outlets 36a and 37a of 36 and 37.

  In this state, high-temperature exhaust is sequentially performed from the engine 11 in the exhaust pipe 20 in accordance with a predetermined explosion order of the engine 11, and the exhaust pressure in the exhaust pipe 20 varies according to the rotation of the engine 11. Therefore, during operation of the engine 11, one branch pipe 32 fitted with one main muffler 36 and the other branch pipe 33 fitted with the other main muffler 37 are caused by pulsation of exhaust pressure in the exhaust pipe 20 or the like. Excited.

  In the present embodiment, in a specific vibration frequency region that is an idle vibration region, the vibration phases of one branch pipe 32 and the other branch pipe 33 are different and cancel each other at the branch point B. Transmission of the vibrations 32 and 33 to the vehicle body side via the center pipe 24 is effectively suppressed. Therefore, unpleasant vibrations are prevented from occurring in the occupant in a specific vibration frequency region due to the exhaust structure that diverts and exhausts air to one main muffler 36 and the other main muffler 37.

  Further, while the arrangement of the one branch pipe 32 and the other branch pipe 33 and the exhaust pipe length are substantially equal, the resonance frequency and vibration mode of both branch pipes 32 and 33 are both branched in a specific vibration frequency region. The pipes 32 and 33 can be set so as to vibrate in substantially opposite phases, and vibration transmission to the vehicle body side can be more effectively suppressed while ensuring a good left and right exhaust balance. Moreover, by adjusting the bending rigidity of the pipe joint 41 portion, the resonance frequency of the branch pipe 32 to which the pipe joint 41 is attached and the phase of vibration in the specific vibration frequency region can be easily adjusted.

  Further, while preventing leakage of exhaust gas at the pipe joint 41 by the seal member 42, the one end side pipe portion 32a and the other end side pipe portion 32b of either one of the branch pipes 32 are relatively relative to each other with a required bending rigidity. Can be made swingable. In addition, the degree of freedom of the mounting posture of the branch pipes 32 and 33 and the main mufflers 36 and 37 is increased, and the pipe joint 41 can be reliably sealed.

  Further, since one branch pipe 32 and the other branch pipe 33 are supported on the vehicle body side in a state where they can vibrate according to their respective bending rigidity, the branch points of the branch pipes 32 and 33 as described above are supported. The vibration in B can be sufficiently canceled out, and it is more effectively prevented that unpleasant vibration is generated in the passenger.

  FIG. 4 is a characteristic diagram of vibration transmission in the low vibration frequency region of the exhaust apparatus having the configuration of the first embodiment of the present invention.

  FIG. 4 (a) shows an exhaust system according to an embodiment in which the exhaust system having the configuration of the present embodiment as described above is mounted on the vehicle 1, and the engine 11 is operated on the acceleration side in a low rotation range (1000 rpm or less). FIG. 4B shows the vibration level of the vertical vibration of the primary rotational component generated on the floor of the front seat of the vehicle (under the driver's feet) when compared with the comparative example. The vibration level of the vertical vibration of the rotating tertiary component in the vicinity is shown in comparison with the comparative example. In both figures, the vibration level generated on the vehicle front seat floor in this embodiment is shown by a solid line, there is no pipe joint 41, one branch pipe corresponding to the branch pipe 32 is provided, the center pipe and the rear pipe. The dotted line indicates the vibration level generated on the front seat floor of the vehicle when the exhaust device of the comparative example in which is connected by a ball joint is used. In this embodiment, since the engine is a four-cycle six-cylinder engine, exhaust from three cylinders is performed in one rotation. For example, if the engine speed is 600 rpm, the exhaust pressure in the exhaust pipe 20 is approximately 3 × 600 ( rpm) / 60 (sec) = 30 Hz.

  As is clear from FIG. 4A, the vibration level of the primary rotation component that deteriorated in the engine speed range (including the idle vibration range) slightly exceeding 550 rpm to 700 rpm in the comparative example is a number in this embodiment. It can be seen that dB is low, and unpleasant idle vibration on the vehicle interior floor in the range of 30 Hz to 40 Hz, which is the frequency region of idle vibration, is sufficiently suppressed.

  Further, as is clear from FIG. 4B, the vibration level of the rotation third-order component is almost the same as that of the rotation first-order component, and corresponds to a range of slightly lower 30 Hz to 40 Hz of the rotation first-order component. It can be seen that the vibration level stably falls within the range, and vibration from the engine 11 and the engine mount 15 side is also reduced. Therefore, the engine mount 15 is returned from the exhaust pipe 20 side to the engine 11 side, and the driver's feet are uncomfortable mainly due to vibration transmission from the engine 11 side and the exhaust pipe 20 side. It can be seen that idle vibration is sufficiently suppressed.

  Thus, in the present embodiment, the vibrations in the specific vibration frequency region of the one branch pipe 32 and the other branch pipe 33, to which the main mufflers 36 and 37 are mounted, cancel each other out at their branch points B. Since the vibration characteristics of the two branch pipes 32 and 33 are made different so that vibration transmission to the side is suppressed, the driver's feet are caused by the exhaust structure that separates and exhausts air to one and the other main mufflers 36 and 37. It is possible to provide an exhaust device that can prevent unpleasant vibrations from occurring on the passenger compartment floor or the like.

(Second Embodiment)
FIG. 5 is a schematic diagram showing a schematic configuration of an exhaust device for a vehicle internal combustion engine according to the second embodiment of the present invention. The present embodiment is substantially the same as the above-described first embodiment in the overall configuration, and only the pipe joint portion is different. Therefore, the same or similar portions are shown in FIGS. The same reference numerals are used for the corresponding components, and only the differences will be described in detail.

  In the present embodiment, as a pipe joint for making the bending rigidity of one branch pipe 32 greatly different from the bending rigidity of the other branch pipe 33, one end side pipe part 32a and the other end side pipe part of one branch pipe 32 are used. A flexible tubular member 51 is provided between the flexible pipe 51b and the flexible tubular member 51. The flexible tubular member 51 is made of, for example, a flexible pipe for exhaust pipe or stainless steel as disclosed in JP-A-5-1532. It is composed of a known flexible metal tube.

  In the present embodiment, the flexible tubular member 51 prevents any exhaust gas from leaking between the one end side pipe portion 32a and the other end side pipe portion 32b of the one branch pipe 32, and either one of the branch pipes. The one end side pipe part 32a and the other end side pipe part 32b of 32 are connected so as to be relatively swingable with a required bending rigidity. Therefore, vibrations in a specific vibration frequency region between the one branch pipe 32 and the other branch pipe 33 to which the main mufflers 36 and 37 are attached cancel each other out at the branch point B of the branch pipes 32 and 33, Vibration transmission can be suppressed, and the same effect as the above-described embodiment can be expected.

  In each of the above-described embodiments, the pipe joint 41 and the flexible tubular member 51 that can function as a vibration blocking mechanism in order to make the bending rigidity of one branch pipe 32 and the other branch pipe 33 different. The pipe joint used to make the resonance frequency and vibration mode of one branch pipe different from that of the other branch pipe is another pipe joint that allows relative branching of both branch pipes. Good. In the above-described embodiment, the V-type 6-cylinder engine has been described as an example. However, the exhaust device for the vehicle internal combustion engine according to the present invention is an idle vibration region (20 Hz to 25 Hz) can be applied to a specific vibration frequency region. For example, the mass of the main mufflers 36 and 37 and the branch pipes 32 and 33 or the rigidity of the pipe joint 41 is different from the above-described example. The specific vibration frequency region in which the phase difference between the vibrations of both the branch pipes 32 and 33 should be increased can be set as appropriate. Further, in any of the embodiments, the pipe joint 41 or the flexible tubular member 51 is mounted on the right branch pipe 32 of the vehicle 1 in order to make the bending rigidity of the branch pipes 32 and 33 greatly different. Needless to say, the left branch pipe 33 may be mounted in reverse.

  As described above, according to the present invention, vibrations in a specific vibration frequency region between one branch pipe and the other branch pipe each equipped with a silencer cancel each other at those branch points, and vibration transmission to the vehicle body side is achieved. Disclosed is an exhaust system for an internal combustion engine for a vehicle that can prevent unpleasant vibrations from occurring due to an exhaust structure that diverts and exhausts air to one and the other silencer. The exhaust device of an internal combustion engine for a vehicle, in particular, the exhaust gas of a multi-cylinder internal combustion engine mounted on the vehicle is divided into one and the other silencer by a branch pipe and exhausted. This is useful for exhaust systems for internal combustion engines for vehicles.

1 is a schematic diagram illustrating a schematic configuration of an exhaust device for an internal combustion engine for a vehicle according to a first embodiment of the present invention. It is a top view which shows the exhaust pipe layout of the exhaust apparatus of the internal combustion engine for vehicles which concerns on the 1st Embodiment of this invention. 1 is a partial cross-sectional front view of a pipe joint that is attached to one branch pipe of an exhaust device for an internal combustion engine for a vehicle according to a first embodiment of the present invention. FIG. 4 is a characteristic diagram of vibration transmission in a low vibration frequency region of an example of an exhaust system having the configuration of the first embodiment of the present invention, where a solid line indicates an example and a dotted line indicates a comparative example. It is a schematic diagram which shows schematic structure of the exhaust apparatus of the internal combustion engine for vehicles which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1 Vehicle 11 Engine (Vehicle Internal Combustion Engine)
11a, 11b Banks 12, 13 Exhaust manifold 15 Engine mount 20 Exhaust pipe 21 First front pipe (upstream part of exhaust pipe)
22 Second front pipe (upstream part of exhaust pipe)
23 Front ball joint 24 Center pipe (middle part of exhaust pipe)
25 Catalytic device 26 Sub-muffler 30 Rear pipe (downstream part of exhaust pipe)
31 Connecting pipe section 32 Branch pipe (one branch pipe)
33 Branch pipe (the other branch pipe)
32a One end side pipe part 32b The other end side pipe part 33 Branch pipe 36 Main muffler (one silencer)
37 Main muffler (other silencer)
36a, 37a Exhaust outlet 41 Pipe joint 42 Seal member 43 Engagement member 44 Spring element 51 Flexible tubular member

Claims (5)

An exhaust pipe of an internal combustion engine mounted on a vehicle is branched into one branch pipe and the other branch pipe downstream from a branch point in the exhaust pipe, and one silencer is connected to the one branch pipe, and the other In the exhaust system for an internal combustion engine for a vehicle, in which the other silencer is mounted on each of the branch pipes,
A pipe joint is provided that allows partial bending of one of the branch pipes upstream of the silencer mounted on one of the one branch pipe and the other branch pipe. ,
When the one branch pipe and the other branch pipe are vibrated in a specific vibration frequency region, the one branch pipe and the other branch pipe are so arranged that the vibrations of both branch pipes cancel each other at the branch point. An exhaust device for an internal combustion engine for a vehicle, wherein at least one of bending rigidity and mass is different from that of the internal combustion engine. The pipe joint is a seal member provided at one end side pipe part of the one of the branch pipes, an engagement member provided at the other end side pipe part of the one of the branch pipes, and the seal member A spring element interposed between the one end side tube portion and the other end side tube portion so as to bias the engagement member to the engagement member, and in a state where the engagement member is in contact with the seal member 2. The exhaust system for an internal combustion engine for a vehicle according to claim 1, wherein the one end side pipe part and the other end side pipe part are connected so as to be relatively swingable. 3. The internal combustion engine for a vehicle according to claim 2 , wherein the engaging member and the seal member are in spherical contact with each other, and the one of the branch pipes can be partially bent in any direction . Exhaust system. The said pipe joint consists of a flexible tubular member interposed between the one end side pipe part of said one branch pipe, and the other end side pipe part of said one branch pipe. Item 2. An exhaust system for an internal combustion engine for a vehicle according to Item 1 . The exhaust pipe is supported on the vehicle body side of the vehicle at an intermediate portion upstream from a branch point where the one branch pipe and the other branch pipe are branched, and the one silencer and the other silencer Each of the devices is supported on the vehicle body side of the vehicle, and the one branch pipe and the other branch pipe are supported by the intermediate portion and the one and the other silencer. The exhaust device for an internal combustion engine for a vehicle according to any one of claims 1 to 4 .

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